The present apparatus is directed to service equipment for valves. In a large valve, the valve body surrounds the valve element. The element typically is a sliding gate or rotatable ball or plug. There is a volume within the valve which is a dead volume, not connected into the flow path. The dead volume is typically filled with a packing grease. The packing grease can vary widely in composition and in purpose. One purpose of the packing grease is to provide a seal lubricant which wets the seals working against the valve element. This will extend the life of the seals. An alternate purpose is to pack the cavity with a grease which is insensitive to a particular temperature range, as, for instance, low temperatures whereby filling with water carrying fluids is prevented. The grease, on exposure to cold temperatures, does not freeze and expand. This prevents damage to the valve body. Extreme damage can occur in the event the valve cavity is filled with water which is frozen, forming cracks in the valve body. There are other reasons for filling the cavity with a packing material.
On occasion, the packing material ought to be changed. It is almost impossible and extremely inconvenient to change the packing material in the cavity, as, for instance, by taking the valve out of service, disassembling the valve and draining the cavity. An alternate approach is installation of grease fittings such as Alemite fittings connecting from the exterior of the valve body to the cavity. The present invention utilizes fittings of this construction or a similar construction. They are typically fabricated into the valve body at the time of construction. They enable the grease or packing material to be inserted into the valve body, as, for instance, under pressure with a grease gun.
The magnitude of the problem cannot be understated. Consider, for instance, an extreme case, perhaps a 36" valve installed outdoors in a northern location. The ambient temperatures may vary from about 90.degree. in the summer to perhaps minus 40.degree. in the winter. This range of variation is extreme; the problems of sticking, expansion or contraction, and viscosity of the grease typically requires the use of a winter grease and a summer grease. A valve sufficiently large for a full bore 36" opening is extremely large, and has a body cavity which holds almost ten barrels of grease. It is a difficult proposition to drain the cavity of this valve. Moreover, it typically cannot be done by taking the valve out of service.
The present invention is an apparatus which enables the grease in a valve body to be changed. In particular, it enables new grease to be inserted under pressure while forcing the previous filled grease out of the body cavity. This is accomplished through the method described hereinbelow, namely, through the use of the fittings taught herein, and a method of draining and filling is thus also disclosed.
The fitting of the present disclosure which enables drainage of the valve cavity utilizes a coupling which threads to a check valve equipped fitting on the valve body. The end located coupling is internally threaded. The body of the apparatus is axially drilled and internally threaded. A stinger which is an elongate rod is mounted on the end of a larger diameter rod having external threads which is located in the passage in the body, and it terminates at the exposed end with a handle. The handle is rotated, thereby threading the stinger rod axially through the fitting and into the pre-existed fitting on the valve body. The stinger contacts and overcomes the check valve mechanism to thereby enable outward drainage. The body is constructed with an internally threaded laterally directed tap hole to permit a drainage hose to be jointed thereto for the purpose of conducting drain grease away to some kind of receptacle. The method of the present invention contemplates the steps of installing the drainage fitting connected to a valve cavity by overcoming the check valve mechanism therebetween to first establish a drainage path from the cavity to the exterior. An injection fitting is also installed in communication with the valve chamber thereby enabling grease to be introduced at another location for the purpose of replacing the grease within the valve chamber.